Heat oil in a large pot on medium heat, and add the celery, onion, carrot and garlic. Stir through and cook for a couple of minutes.
Add the rest of the ingredients, bring to a boil and simmer for 60 min, stirring occasionally
By this stage, the potato and pumpkin should begin to dissolve. With a large spatula or spoon press the potato and pumpkin up against the sides of the pot to help mash the lumpy bits. This will naturally thicken the soup. simmer for a further 15 min.
Cook some pasta separately now or add to the soup if you are planning on eating it all in one sitting. Simmer for another 15 min or until pasta is cooked through and serve with some crusty bread. (If you are cooking the pasta separately simply add a good spoonful of cooked pasta to each bowl when serving.